Abstract
The influence of i.a. infusions of equivalent doses of prostaglandins (PG) E1, E2, F1α and F2α on vasoconstrictor responses to norepinephrine and sympathetic nerve stimulation were evaluated in the dog hindpaw perfused at constant flow. Infusions of PGE1 and PGE2,1 µg/min, decreased vascular resistance in the hindpaw. PGE1 markedly reduced responses to i.a. norepinephrine, angiotensin and sympathetic nerve stimulation whereas PGE2 did not alter these responses. However, when the infusion rate was increased to 2 µg/min, responses to nerve stimulation, but not norepinephrine, were enhanced. Infusion of PGF1α, and PGF2α, 1 µg/min, caused no change in vancular resistance in the hindpaw but enhanced the response to sympathetic nerve stimulation. PGF1α, decreased the response to norepinephrine whereas PGF2α, was without effect. These results suggest that PGF2α may enhance adrenergic transmission in the hindpaw by facilitating the release of transmitter from sympathetic nerve endings and that PGE1 may decrease the sensitivity of the cutaneous vessels to norepinephrine by a nonspecific effect. These data provide further support for the postulate that, by a variety of mechanisms, prostaglandins may serve as modulators of adrenergic responses in vascular smooth muscle.
Footnotes
- Received October 28, 1970.
- Accepted February 17, 1971.
- © 1971 by The Williams & Wilkins Co.
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